Information recording medium, information recording device and information reproducing device for the same

ABSTRACT

An optical disk is provided that disables reproduction of sub-information even if the sub-information as a contents encryption key is recorded entirely onto another optical disk. Sub-information is recorded on the optical disk by deforming a recording mark slightly in accordance with a pseudo random number sequence that is obtained using as an initial value medium ID that is read out medium inherent information. This allows sub-information inherent in a medium to be recorded, and even if the sub-information is duplicated entirely to another optical disk, the illegally duplicated sub-information cannot be reproduced because of a difference in initial value of a pseudo random number sequence between media.

TECHNICAL FIELD

The present invention relates to an information recording medium, andinformation recording apparatus and information reproducing apparatusfor the information recording medium. Specifically, this inventionrelates to a technique of recording sub-information as a contentsencryption key on an information recording medium so that thesub-information is superimposed on main information and reproducing thesub-information recorded on the information recording medium.

BACKGROUND ART

Optical disks typified by a DVD-RAM have become widespread asinformation recording media on which massive amounts of digital datasuch as AV (Audio Video) data, computer data and the like can berecorded. In order to secure the sound distribution of digital worksrecorded on such information recording media, there is a demand for atechnique that prevents digital works on an information recording mediumfrom being duplicated illegally to another information recording medium.

One conventional technique for preventing illegal duplication is suchthat in accordance with a pseudo random number sequence that isgenerated inside a given apparatus, an edge in a tangential direction ofa recording mark to be recorded on an optical disk is displaced to aposition advanced or delayed by a constant slight amount, thus recordingsub-information. Such a technique is proposed as a method of recordingkey information, as sub-information, for decoding encrypted contentsrecorded on an optical disk (see, for example, JP2001-357533 A).

FIG. 23 is a circuit block diagram schematically showing a configurationof a conventional information recording apparatus that recordssub-information by displacing an edge in a tangential direction of arecording mark by a constant slight amount.

In FIG. 23, upon receipt of an initialization timing signal (INIT) froma main information recording part (not shown), which indicates a timingfor recording sub-information, a pseudo random number generator 2301initializes a pseudo random number sequence using an initial value 2302that has been stored in advance secretly inside an apparatus, generatesa pseudo random number sequence (PRS) in synchronization with a byteclock from the main information recording part (not shown), and outputsit to an exclusive OR circuit (XOR) 2303.

The XOR 2303 performs an exclusive OR operation of sub-information(contents encryption key) (SI) to be recorded and the pseudo randomnumber sequence from the pseudo random number generator 2301 so as tooutput a sub-information recording control signal (SIW) to a phaseencoding (PE) modulator 2304.

In the PE modulator 2304, the sub-information recording control signalSIW outputted from the XOR 2303 is subjected to PE modulation so as togenerate a phase modulation control signal (PMC), and the phasemodulation control signal (PMC) is transmitted to a recording channel.Based on this phase modulation control signal PMC, modulation isperformed in which an edge of a recording signal for recording maininformation is advanced or delayed, and thus the contents encryption keyis recorded as sub-information.

Furthermore, in an information reproducing apparatus, sub-information isreproduced based on a correlation of a phase error signal obtained as aresult of detecting whether an edge of a reproduced signal of maininformation is advanced or delayed with a pseudo random number sequencegenerated based on an initial value that is the same as used in the caseof the information recording apparatus.

In the above-described technique, since sub-information (contentsencryption key) is superimposed as jitter of a reproduced signal, unlessan accurate pseudo random number sequence can be generated, it isimpossible to record or reproduce sub-information appropriately. Thisallows digital works recorded on an optical disk to be protected fromillegal duplication.

However, in this technique, it is required that all apparatuses use astandardized pseudo random number generator and an initial value thereofBecause of this, particularly, once the initial value is publicized,proof of every illegal duplication might be lost. Thus, the initialvalue should be managed strictly.

Furthermore, in considering such information recording/reproducingapparatuses that record and reproduce main information andsub-information, once an area in which sub-information is recorded isrevealed, it hardly can be said that there is sufficient proof of an actof recording encrypted contents and an encryption key of the encryptedcontents recorded as sub-information entirely onto another optical disk.

DISCLOSURE OF THE INVENTION

With the foregoing in mind, it is an object of the present invention toprovide an information recording medium that disables reproduction ofsub-information even if the sub-information as a contents encryption keyis recorded entirely onto another information recording medium, ornullifies recording and reproduction of sub-information by an apparatusif an initial value is publicized in the apparatus, and to provide aninformation recording apparatus and an information reproducing apparatuswith respect to the information recording medium.

In order to achieve the above-mentioned object, a first informationrecording medium according to the present invention is an informationrecording medium in which a recording mark is formed as main informationby switching a signal level at a predetermined interval of a referencesignal and that has the following configuration. That is, in theinformation recording medium, sub-information is recorded by deformationof a shape or a pattern of the recording mark (for example, displacementof a recording mark edge in a tangential direction) or positionaldisplacement of the recording mark (for example, displacement of therecording mark itself in a radial direction) based on thesub-information and medium inherent information of the informationrecording medium.

According to this configuration, even if in addition to maininformation, sub-information itself also is duplicated entirely toanother information recording medium, the duplicated sub-informationcannot be reproduced using a pseudo random number sequence inherent inthe other information recording medium.

In order to achieve the above-mentioned object, a second informationrecording medium according to the present invention is an informationrecording medium in which a recording mark is formed as main informationby switching a signal level at a predetermined interval of a referencesignal and that has the following configuration. That is, in theinformation recording medium, sub-information is recorded by deformationof a shape or a pattern of the recording mark (for example, displacementof a recording mark edge in a tangential direction) or positionaldisplacement of the recording mark (for example, displacement of therecording mark itself in a radial direction) based on thesub-information and apparatus nullification information for nullifyingrecording and reproduction of the main information recorded on theinformation recording medium. In this case, the apparatus nullificationinformation is an encryption key set that encrypts the main informationof the information recording medium.

According to this configuration, for example, in the case wheresub-information recorded on an information recording medium isduplicated illegally by tampering with or alteration to an apparatus,recording and reproduction of the sub-information by such an illegalapparatus can be nullified.

In order to achieve the above-mentioned object, a third informationrecording medium according to the present invention is an informationrecording medium in which a recording mark is formed as main informationby switching a signal level at a predetermined interval of a referencesignal and that has the following configuration. That is, in theinformation recording medium, sub-information is recorded by deformationof a shape or a pattern of the recording mark (for example, displacementof a recording mark edge in a tangential direction) or positionaldisplacement of the recording mark (for example, displacement of therecording mark itself in a radial direction) based on thesub-information and apparatus inherent information of an apparatus thathas recorded the main information on the information recording medium.

According to this configuration, apparatuses other than an apparatusthat has performed recording with respect to an information recordingmedium cannot reproduce sub-information from the information recordingmedium.

In order to achieve the above-mentioned object, a first informationrecording apparatus according to the present invention has aconfiguration including: a main information recording unit that records,in synchronization with a predetermined reference signal, maininformation by forming a recording mark at discrete reference positionson an information recording medium; a random number sequence generatingunit that reads out medium inherent information of the informationrecording medium and generates a pseudo random number sequence relatedto the medium inherent information; and a sub-information recording unitthat records sub-information so that the sub-information is superimposedon the main information by deformation of a shape or a pattern of therecording mark (for example, displacement of a recording mark edge in atangential direction) or positional displacement of the recording mark(for example, displacement of the recording mark itself in a radialdirection) based on the sub-information and the pseudo random numbersequence generated by the random number sequence generating unit.

According to this configuration, it is possible to recordsub-information that cannot be reproduced using a pseudo random numbersequence inherent in another medium even if in addition to maininformation, the sub-information itself also is duplicated entirely tothe another medium.

In order to achieve the above-mentioned object, a second informationrecording apparatus according to the present invention has aconfiguration including: a main information recording unit that records,in synchronization with a predetermined reference signal, maininformation by forming a recording mark at discrete reference positionson an information recording medium; a random number sequence generatingunit that generates a pseudo random number sequence related to apparatusnullification information that is recorded on the information recordingmedium; and a sub-information recording unit that recordssub-information so that the sub-information is superimposed on the maininformation by deformation of a shape or a pattern of the recording markfor example, displacement of a recording mark edge in a tangentialdirection) or positional displacement of the recording mark (forexample, displacement of the recording mark itself in a radialdirection) based on the sub-information and the pseudo random numbersequence generated by the random number sequence generating unit.

According to this configuration, it is possible to recordsub-information that can nullify recording and reproduction of thesub-information with respect to an apparatus that is used illegally byillegal tampering and alteration.

In order to achieve the above-mentioned object, a third informationrecording apparatus according to the present invention has aconfiguration including: a main information recording unit that records,in synchronization with a predetermined reference signal, maininformation by forming a recording mark at discrete reference positionson an information recording medium; a random number sequence generatingunit that generates a pseudo random number sequence related to apparatusinherent information that is contained individually in each apparatus;and a sub-information recording unit that records sub-information sothat the sub-information is superimposed on the main information bydeformation of a shape or a pattern of the recording mark for example,displacement of an edge in a tangential direction of the recording mark)or positional displacement of the recording mark (for example,displacement of the recording mark in a radial direction) based on thesub-information and the pseudo random number sequence generated by therandom number sequence generating unit.

According to this configuration, it is possible to recordsub-information that cannot be reproduced by apparatuses other than anapparatus that has performed recording with respect to an informationrecording medium.

Furthermore, the second information recording apparatus has aconfiguration including an apparatus nullification processing unit thatgenerates an encryption key for encrypting the main information bydecoding the encrypted apparatus nullification information that isrecorded on the information recording medium using apparatus inherentinformation of an apparatus that performs recording with respect to theinformation recording medium.

According to this configuration, even with the advent of an apparatusthat rewrites sub-information illegally by tampering or the like, byupdating from then on an encryption medium key bundle that is apparatusnullification information of each medium being distributed, it ispossible to nullify recording of the sub-information on a medium havingthe updated encryption medium key bundle.

In order to achieve the above-mentioned object, a first informationreproducing apparatus according to the present invention has aconfiguration including: a main information reproducing unit thatreproduces main information from a recorded mark having a length that isan integral multiple of a discrete reference interval on an informationrecording medium; a dock extracting unit that extracts a dock that issynchronized with the reference interval from a reproduced signalobtained when the recorded mark is reproduced; a random number sequencegenerating unit that reads out medium inherent information of theinformation recording medium and generates a pseudo random numbersequence related to the medium inherent information; and asub-information reproducing unit that reproduces sub-information basedon the reproduced signal reproduced by the main information reproducingunit, the dock extracted by the dock extracting unit, and the pseudorandom number sequence generated by the random number sequencegenerating unit.

According to this configuration, it is possible to realize aninformation reproducing apparatus that cannot reproduce sub-informationof an illegally duplicated medium.

In order to achieve the above-mentioned object, a second informationreproducing apparatus according to the present invention has aconfiguration including: a main information reproducing unit thatreproduces main information from a recorded mark having a length that isan integral multiple of a discrete reference interval on an informationrecording medium; a dock extracting unit that extracts a dock that issynchronized with the reference interval from a reproduced signalobtained when the recorded mark is reproduced; a random number sequencegenerating unit that generates a pseudo random number sequence relatedto apparatus nullification information recorded on the informationrecording medium; and a sub-information reproducing unit that reproducessub-information based on the reproduced signal reproduced by the maininformation reproducing unit, the dock extracted by the dock extractingunit, and the pseudo random number sequence generated by the randomnumber sequence generating unit.

According to this configuration, it is possible to realize aninformation reproducing apparatus that disables reproduction ofsub-information by a nullified apparatus.

In order to achieve the above-mentioned object, a third informationreproducing apparatus according to the present invention has aconfiguration including: a main information reproducing unit thatreproduces main information from a recorded mark having a length that isan integral multiple of a discrete reference interval on an informationrecording medium; a dock extracting unit that extracts a dock that issynchronized with the reference interval from a reproduced signalobtained when the recorded mark is reproduced; a random number sequencegenerating unit that generates a pseudo random number sequence relatedto medium inherent information that is contained individually in eachapparatus; and a sub-information reproducing unit that reproducessub-information based on the reproduced signal reproduced by the maininformation reproducing unit, the dock extracted by the dock extractingunit, and the pseudo random number sequence generated by the randomnumber sequence generating unit.

According to this configuration, it is possible to realize aninformation reproducing apparatus that allows sub-information to bereproduced only by an apparatus that has performed recording withrespect to an information recording medium.

Furthermore, the second information reproducing apparatus has aconfiguration including an apparatus nullification processing unit thatgenerates a decoding key for decoding the main information by decodingthe encrypted apparatus nullification information that is recorded onthe information recording medium using apparatus inherent information ofan apparatus that performs reproduction with respect to the informationrecording medium.

According to this configuration, even with the advent of an apparatusthat rewrites sub-information illegally by tampering or the like, byupdating from then on an encryption medium key bundle that is apparatusnullification information of each medium being distributed, it ispossible to nullify reproduction of the sub-information from a mediumhaving the updated encryption medium key bundle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a timing chart schematically showing a state in which arecording mark containing sub-information is formed on an optical diskas an information recording medium according to Embodiment 1 of thepresent invention.

FIG. 2 is a conceptual diagram showing a signal connection relationshipbetween the optical disk as the information recording medium and anoptical disk recording apparatus as an information recording apparatusaccording to Embodiment 1 of the present invention.

FIG. 3 is a block diagram mainly showing an example of a configurationof an information recording part 202 shown in FIG. 2.

FIG. 4 is a circuit block diagram showing an example of an internalconfiguration of a random number generator 304 shown in FIG. 3.

FIG. 5 is a circuit block diagram showing an example of an internalconfiguration of a phase modulator 307 shown in FIG. 3.

FIG. 6 is a detailed timing chart for signals in respective portionswhen a recording mark containing sub-information is formed on theoptical disk by the information recording part 202 that is configured asin FIG. 3.

FIG. 7 is conceptual diagram showing a signal connection relationshipbetween the optical disk and an optical disk reproducing apparatus as aninformation reproducing apparatus according to Embodiment 1 of thepresent invention.

FIG. 8 is a block diagram mainly showing an example of a configurationof an information reproducing part 702 shown in FIG. 7.

FIG. 9 is a circuit block diagram showing an example of an internalconfiguration of a reproduced signal processing circuit 805 shown inFIG. 8.

FIG. 10 is a circuit block diagram showing an example of an internalconfiguration of a sub-information detector 809 shown in FIG. 8.

FIG. 11 is a detailed timing chart for signals in respective portionswhen sub-information is reproduced from a recorded mark on the opticaldisk by the information reproducing part 702.

FIG. 12 is a waveform chart showing a relationship between asub-information bit and an output voltage of an integrator 1002 includedin the sub-information detector 809 shown in FIG. 8.

FIG. 13 is a conceptual diagram showing a signal connection relationshipbetween an optical disk as an information recording medium and anoptical disk recording apparatus as an information recording apparatusaccording to Embodiment 2 of the present invention.

FIG. 14 is a conceptual diagram showing a signal connection relationshipbetween the optical disk as the information recording medium and anoptical disk reproducing apparatus as an information reproducingapparatus according to Embodiment 2 of the present invention.

FIG. 15 is a conceptual diagram showing a signal connection relationshipbetween an optical disk as an information recording medium and anoptical disk recording apparatus as an information recording apparatusaccording to Embodiment 3 of the present invention.

FIG. 16 is a conceptual diagram showing a signal connection relationshipbetween the optical disk as the information recording medium and anoptical disk reproducing apparatus as an information reproducingapparatus according to Embodiment 3 of the present invention.

FIG. 17 is a diagrammatic view showing an example of recorded markscontaining sub-information that are formed on an optical disk as aninformation recording medium according to Embodiment 4 of the presentinvention.

FIG. 18 is a block diagram showing an example of a configuration of anoptical disk recording apparatus as an information recording apparatusaccording to Embodiment 4 of the present invention.

FIG. 19 is a timing chart for signals in respective portions when arecording mark containing sub-information is formed on an optical diskby the optical disk recording apparatus that is configured as in FIG.18.

FIG. 20 is a block diagram showing an example of a configuration of anoptical disk reproducing apparatus as an information reproducingapparatus according to Embodiment 4 of the present invention.

FIG. 21 is a timing chart for signals in respective portions whensub-information is reproduced from a recorded mark on an optical disk bythe optical disk reproducing apparatus that is configured as in FIG. 20.

FIG. 22 is a schematic plan view showing areas in which disk inherentidentification information as medium inherent information and anencryption medium key bundle as apparatus nullification information havebeen recorded in advance, respectively, on each of the optical disksaccording to the embodiments of the present invention.

FIG. 23 is a circuit block diagram schematically showing a configurationof a conventional information recording apparatus that recordssub-information by displacing an edge in a tangential direction of arecording mark by a constant slight amount.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed by referring to the appended drawings. Each of the followingembodiments describes the case where an optical disk is used as aninformation recording medium, and an information recording apparatus andan information reproducing apparatus are an optical disk recordingapparatus and an optical disk reproducing apparatus, respectively.

Embodiment 1

FIG. 1 is a timing chart schematically showing a state in which arecording mark containing sub-information is formed on an optical diskas an information recording medium according to Embodiment 1 of thepresent invention.

Disk inherent identification information as information inherent in amedium has been recorded in advance on the optical disk according tothis embodiment. On the optical disk, not only is main informationrecorded by formation of an optically readable recording mark but alsoat the same time, watermark information is recorded as sub-informationwhile being embedded in the main information by phase modulation inwhich edges in a tangential direction of recording marks 101 and 102 tobe formed in a data portion 104 other than a synchronization portion 103are advanced or delayed in phase by Δt.

FIG. 1 shows an optical disk in which, with respect to an edge in thetangential direction of a standard recording mark (SRM) synchronizedwith a synchronization clock (SCLK) constituting main information,sub-information is recorded only in a section that indicates the dataportion 104 in which the sub-information is to be embedded and in whicha phase modulation enabling signal (PME) is at a logic “H” level. At atiming indicated by a random number initialization timing signal (INIT),the sub-information is related to a sub-information correlation randomnumber sequence (SICS) (for example, exclusive OR is performed) that isinitialized using a value calculated from disk inherent identificationinformation of a medium with respect to which recording is to beperformed. Moreover, based on a post-PE modulation random numbersequence (PERS) obtained as a result of PE modulation performed so thatan edge in the tangential direction is advanced or delayed in phase by abyte unit substantially uniformly, an edge of a recording mark of themain information is phase-modulated in the tangential direction, andthus a modulated recording mark (MRM) is recorded.

The description is directed next to a recording apparatus with respectto an optical disk on which, in accordance with a pseudo random numbersequence generated using disk inherent identification information as aninitial value, sub-information is recorded so that the sub-informationis superimposed on main information. The optical disk recordingapparatus according to this embodiment is an apparatus that records maininformation and sub-information on an optical disk.

FIG. 2 is a conceptual diagram showing a signal connection relationshipbetween the optical disk and the optical disk recording apparatusaccording to this embodiment.

The optical disk recording apparatus according to this embodiment readsout from an optical disk with respect to which recording is to beperformed disk inherent identification information as medium inherentinformation that has been recorded in advance on the optical disk. Thisdisk inherent identification information is inherent in each and everyoptical disk and as shown in FIG. 22, is recorded in a BCA (BurstCutting Area) 2201 by an initializer using a laser whose output ishigher than that used in the case of normal information recording.Therefore, without an initializer, general users cannot perform illegaltampering and duplication with respect to this disk inherentidentification information that is the medium inherent information.Incidentally, in FIG. 22, reference numeral 2203 and 2204 denote a userarea and an outer rim control area, respectively.

In FIG. 2, the optical disk recording apparatus is composed of aninformation storing part 201 that stores disk inherent identificationinformation that has been read out in advance from the BCA and aninformation recording part 202 that records main information andsub-information using the disk inherent identification information thathas been stored in advance in the information storing part 201.

FIG. 3 is a block diagram mainly showing an example of a configurationof the information recording part 202 shown in FIG. 2. In FIG. 3, theinformation recording part 202 is composed of a timing generator 301, amodulator 302, a random number initial value generator 303, a randomnumber generator 304, a random number sequence converter 305, a PE(Phase Encoding) modulator 306, a phase modulator 307, a recordingchannel 308, and a recording head 309.

Receiving from a controller or the like, which is not shown,notification that recording of main information and sub-information isstarted, the timing generator 301 supplies the modulator 302 and therandom number generator 304 with a synchronization signal (SYNC)indicating a timing for inserting a synchronization pattern(synchronization portion) in recording data. Further, based on thissynchronization signal SYNC and a clock signal (SCLK), insynchronization with each byte of the recording data, the timinggenerator 301 outputs to the random number generator 304 a byte clock(BCLK) that is obtained by 16-frequency-division of the clock signalSCLK. The timing generator 301 further supplies the PE modulator 306with a PE signal (PE) in which a logic “H” level section and a logic “L”level section are allocated equally with respect to each byte. Moreover,in order to record the main information and the sub-information, thetiming generator 301 supplies the phase modulator 307 with a phasemodulation enabling signal (PME) indicating a portion in which thesub-information is to be recorded (for example, a data portion of aframe without an ID portion).

Based on the synchronization signal SYNC from the timing generator 301,the modulator 302 inserts a synchronization pattern (synchronizationportion) in inputted recording data (main information). The modulator302 further converts each 8-bit length code (byte) of the maininformation to be recorded into a corresponding 16-bit length code andthen converts the 16-bit length code into a NRZI (Non-Return-to-ZeroInverted) code so as to generate a channel signal (CH) and supplies itto the phase modulator 307.

Based on disk inherent identification information (Medium ID in FIG. 3)that has been read out in advance from an optical disk 310 and storedtemporarily in the information storing part 202 (FIG. 2) prior toinformation recording, the random number initial value generator 303calculates an initial value for the random generator 304. In thisembodiment, the random number initial value generator 303 has aconfiguration in which disk inherent identification information (64bits) that has been stored temporarily by the information storing part202 is outputted in an as-is state as an initial value (INITV) of arandom number sequence.

The random umber generator 304 presets the initial value outputted fromthe random number initial value generator 303 at a timing of thesynchronization signal SYNC from the timing generator 301 and generates1 bit of a random number sequence (M sequence) at a timing of the byteclock BCLK.

FIG. 4 is a circuit diagram showing an example of an internalconfiguration of the random number generator 304. In FIG. 4, the randomnumber generator 304 is a pseudo random number generator that generates(the 64^(th) power of 2−1) bit sequences in one cycle and is formed of ashift resister 401 with a bit length of 64 bits. The shift resistor 401is shifted to the left by 1 bit at a timing of the byte clock BCLK, andan exclusive OR of the respective output values of a bit [63] (MSB), abit [4], a bit [3], and a bit [1] is fed back to a bit [0] (LSB). Thebit [0] (LSB) thus generated is supplied as a pseudo random numbersequence (PRS) to the random number sequence converter 305.

Referring back to FIG. 3, the random number sequence converter 305performs an operation for correlating each bit of sub information to berecorded with the pseudo random number sequence from the random numbergenerator 304. In this embodiment, the random number sequence converter305 is formed of an exclusive OR circuit. In accordance with each bit ofthe sub-information to be recorded, the random number sequence converter305 performs inversion/non-inversion of the pseudo random numbersequence PRS and supplies to the PE modulator 306 a resultant sequenceas a sub-information correlation sequence (SICS). That is, the randomnumber sequence converter 305 generates the sub-information correlationsequence SICS by updating a sub-information bit with respect to eachpredetermined area (3 frames in this embodiment) in which 1 bit ofsub-information is to be recorded.

Based on the PE signal from the timing generator 301, the PE modulator306 performs PE modulation (inversion after an exclusive OR) withrespect to the sub-information correlation sequence SICS outputted fromthe random number sequence converter 305 and supplies to the phasemodulator 307 a resultant sequence as a PE modulation random numbersequence (PERS) of a sequence on which the sub-information issuperimposed. As a result, the PE modulation random number sequence PERSfalls in the middle of a channel signal CH in the case where thesequence on which the sub-information is superimposed is at the logic“L” level and rises in the middle of the channel signal in the casewhere the sequence on which the sub-information is superimposed is atthe logic “H” level, and even in the case where the same random numbersequences are provided continuously, the logic “L” level section and thelogic “H” level section are allocated substantially equally.

The phase modulator 307 supplies the channel signal CH to the recordingchannel 308 in the following manner. That is, based on the PE modulationrandom number sequence PERS from the PE modulator 306, with respect onlyto a data portion of a frame, in which sub-information is to berecorded, of the channel signal CH from the modulator 302 (when thephase modulation enabling signal PME is at the logic “H” level), phasemodulation is performed in which an edge in the tangential direction isdelayed or advanced by a constant slight amount of time. On the otherhand, with respect to portions other than the data portion (when thephase modulation enabling signal PME is at the logic “L” level), an edgein the tangential direction is not phase-modulated.

FIG. 5 is a circuit diagram showing an example of an internalconfiguration of the phase modulator 307. In FIG. 5, the phase modulator307 is composed of delayers 502, 503, and 504 that delay signals by theabove-mentioned slight amount of time and a selector 501 with threeinputs and one output. In the case where the phase modulation enablingsignal PME inputted as a control signal is at the logic “L” level, theselector 501 outputs a signal CH (2) (not changed in phase) obtained bydelaying the channel signal CH from the modulator 302 at the delayer 502in a first stage. Further, in the case where the phase modulationenabling signal PME is at the logic “H” level and the PE modulationrandom number sequence PERS is at the logic “H” level, the selector 501outputs the channel signal CH from the modulator 302 in an as-is stateas CH (1) (phase advance: −Δt). Further, in the case where the phasemodulation enabling signal PME is at the logic “H” level and the PEmodulation random number sequence PERS is a the logic “L” level, theselector 501 outputs a signal CH (3) (phase delay: +Δt) obtained bydelaying the channel signal from the modulator 302 at the delayers (503and 504) in a second stage.

As a result, with respect to a frame on which sub-information is notsuperimposed and a synchronization portion, an edge in the tangentialdirection of a recording mark is not changed in phase, while withrespect to a data portion on which sub-information is superimposed, thephase is advanced by the above-mentioned slight amount of time Δt whenthe PE modulation random number sequence is at the logic “H” level anddelayed by the above-mentioned slight amount of time Δt when the PEmodulation random number sequence is at the logic “L” level.

Referring again back to FIG. 3, in synchronization with logic “H/L” of amodulated channel signal MCH from the phase modulator 307, the recordingchannel 308 generates a control signal that changes the recording powerof a laser beam to be outputted to the optical disk 310, and supplies itto the recording head 309.

Based on the control signal from the recording channel 308, therecording head 309, while adjusting the power of a laser beam, forms anoptically readable modulated recording mark on the optical disk 310.

The description is directed next to a recording action of the opticaldisk recording apparatus according to this embodiment by referring toFIG. 6. FIG. 6 is a detailed timing chart for signals in respectiveportions when a modulated recording mark MRM containing sub-informationis formed on the optical disk 310.

The timing generator 301 supplies the modulator 302 and the randomnumber generator 304 with the synchronization signal SYNC synchronizedwith the inputted clock signal SCLK. When the synchronization signalSYNC outputted from the timing generator 301 is at the logic “H” level,the modulator 302 outputs the recording channel signal CH constituting asynchronization portion 601 to the phase modulator 307. Further, whenthe synchronization signal SYNC is at the logic “L” level, the modulator302 performs modulation of main information to be recorded (for example,8-16 modulation in the case of a DVD-RAM) and outputs the recordingchannel signal CH constituting a data portion 602 to the phase modulator307. Further, the timing generator 301 outputs to the phase modulator307 the phase modulation enabling signal PME that allows the logic “H”level to be attained in a time period of the data portion 602 in whichsub-information is superimposed and recorded.

The random number initial value generator 303 outputs disk inherentidentification information (of 64 bits, for example) in an as-is state,which has been read out in advance from the optical disk 310 and storedin the information storing part 201 (FIG. 2) prior to data recording, tothe random number generator 304 as the initial value INITV During thetime when the synchronization signal SYNC outputted from the timinggenerator 301 is at the logic “H” level, the random number generator 304presets the disk inherent identification information from the randomnumber initial value generator 303 so as to perform initialization. Whenthe synchronization signal SYNC is at the logic “L” level, insynchronization with the byte clock BCLK from the timing generator 301,the random number generator 304 generates the pseudo random numbersequence PRS 1 bit at a time and outputs it to the random numbersequence converter 305.

The random number sequence converter 305 performs a bit operation(exclusive OR in this embodiment) with respect to sub-information to berecorded and the pseudo random number sequence PRS from the randomnumber generator 304, generates the sub-information correlation sequenceSICS (in the case where sub-information to be recorded is at the logic“L” level, a sequence equivalent to the pseudo random number sequencePRS; and in the case where sub-information to be recorded is at thelogic “H” level, a sequence obtained by inverting the pseudo randomnumber sequence PRS), and outputs it to the PE modulator 306. FIG. 6shows the case where each bit of sub-information to be recorded is atthe logic “L” level. Therefore, in this case, the sub-informationcorrelation sequence SICS is a sequence equivalent to the pseudo randomnumber sequence PRS. Moreover, based on the PE signal from the timinggenerator 301, the PE modulator 306 generates the PE modulation randomnumber sequence PERS obtained by performing PE modulation with respectto the sub-information correlation sequence SICS from the random numbersequence converter 305 and outputs it to the phase modulator 307.

When the phase modulation enabling signal PME from the timing generator301 is at the logic “L” level, the phase modulator 307 outputs to therecording channel 308 the channel signal CH from the modulator 302 in anas-is state as the modulated channel signal MCH. Further, when the phasemodulation enabling signal PME is at the logic “H” level, the phasemodulator 307 advances or delays an edge of the channel signal CHaccording to a value of the PE modulation random number sequence PERSfrom the PE modulator 306. In this embodiment, in a time period in whichthe phase modulation enabling signal PME is at the logic “H” level, inthe case where the PE modulation random number sequence PERS is at thelogic “H” level, an edge in the tangential direction of the channelsignal CH is advanced by Δt, and conversely, in the case where the PEmodulation random number sequence PERS is at the logic “L” level, anedge of the channel signal CH is delayed by Δt. Thus, the modulatedchannel signal MCH is generated and outputted to the recording channel308. Using the modulated channel signal MCH thus generated, a recordinglaser is controlled so as to form modulated recording marks MRM (603 and604) on the optical disk 310.

The description is directed next to an optical disk reproducingapparatus that reproduces main information and sub-information from anoptical disk in accordance with a pseudo random number sequence PRSgenerated by initialization using medium inherent information.

FIG. 7 is conceptual diagram showing a signal connection relationshipbetween the optical disk and an optical disk reproducing apparatusaccording to this embodiment. In FIG. 7, the optical disk reproducingapparatus is composed of an information storing part 701 thattemporarily stores disk inherent identification information that hasbeen read out in advance from the BCA (FIG. 22) and an informationreproducing part 702 that reproduces main information andsub-information using the disk inherent identification information thathas been stored in advance in the information storing part 701.

FIG. 8 is a block diagram mainly showing an example of a configurationof the information reproducing part 702 shown in FIG. 7. In FIG. 8, theinformation reproducing part 702 is composed of a reproducing head 802,a reproducing channel 803, a clock extractor 804, a reproduced signalprocessing circuit 805, a random number initial value generating part806, a random number generator 807, a PE modulator 808, and asub-information detector 809.

The reproducing head 802 focuses and irradiates a light beam on arecorded mark on an optical disk 801 being rotated, receives reflectedlight thereof with a photodiode, and then amplifies the reflected lightso as to generate an analog read-out signal (ARD) and supply it to thereproducing channel 803.

The reproducing channel 803 converts the analog read-out signal ARD fromthe reproducing head 802 into a digital read-out signal (DRD) byequalizing or shaping the waveform of the signal and supplies thedigital read-out signal DRD to each of the clock extractor 804 and thereproduced signal processing circuit 805.

Based on the digital read-out signal DRD from the reproducing channel303, the clock extractor 804 generates a channel clock (CHCLK)synchronized with a channel bit and supplies it to the reproduced signalprocessing circuit 805. Further, the clock extractor 804 generates abyte clock (BCLK) synchronized with each piece of recording data (byteunit) in the digital read-out signal DRD and supplies it to each of thereproduced signal processing circuit 805, the random number generator807, and the sub-information detector 809. Further, at the same time,with reference to the channel clock CHCLK, the clock extractor 804detects a phase error of the digital read-out signal DRD. In the casewhere phase advance is detected, the clock extractor 804 generates aleading phase error signal (LEAD ERR) and supplies it to thesub-information detector 809, and in the case where phase delay isdetected, the clock extractor 804 generates a lagging phase error signal(LAG ERR) and supplies it to the sub-information detector 809.

The reproduced signal processing circuit 805 detects a synchronizationportion from the digital read-out signal DRD from the reproducingchannel 303 and demodulates a channel signal CH (main information) fromthe digital read-out signal DRD with reference to the synchronizationportion.

FIG. 9 is a circuit block diagram showing an example of an internalconfiguration of the reproduced signal processing circuit 805. In FIG.9, the reproduced signal processing circuit 805 is composed of ademodulator 901, a synchronization signal detector 902, and a gatesignal generator 903.

The synchronization signal detector 902 detects a synchronizationportion (synchronization pattern) contained in the digital read-outsignal DRD, generates a synchronization signal (SYNC), and outputs it toeach of the clock extractor 804 and the random number generator 807.

The demodulator 901 is a demodulator with respect to the modulator ofthe optical disk recording apparatus. By the demodulator 901, thedigital read-out signal DRD from the reproducing channel 803 is sampledin synchronization with the channel clock CHCLK from the clock extractor804 and is converted into an 8-bit channel signal CH corresponding to a16-bit channel code in synchronization with the byte clock BCLK from theclock extractor 804 to be outputted as main information.

Furthermore, with reference to the synchronization signal SYNC, the gatesignal generator 903 outputs to the sub-information detector 809 asub-information detection enabling signal (SIDE) that is a signalindicating a data portion of each frame in which sub-information isrecorded frame other than leading and final frames of each sector).

Referring back to FIG. 8, the random number initial value generator 806calculates an initial value (INITV) of a random number from diskinherent identification information (of 64 bits, for example) that hasbeen read out in advance from the BCA (FIG. 22) on the optical disk 801and stored primarily in the information storing part 701 (FIG. 7) andsupplies it to the random number generator 807. In this embodiment,similarly to the above-described disk recording apparatus, the randomnumber initial value generator 806 supplies to the random numbergenerator 807 the disk inherent identification information in an as-isstate as the initial value INITV of the random number.

The random number generator 807 has the same function as that of therandom number generator 304 (FIG. 3) of the optical disk recordingapparatus. That is, the random number generator 807 presets the initialvalue INITV from the random number initial value generator 806 at atiming of the synchronization signal SYNC from the reproduced signalprocessing circuit 805 and generates a pseudo random number sequence PRS(M sequence) at a timing of the byte clock BCLK from the clock extractor804.

The PE modulator 808 has the same function as that of the PE modulator306 (FIG. 3) of the optical disk recording apparatus. That is, based ona PE signal from the clock extractor 804, the PE modulator 808 performsPE modulation with respect to the pseudo random number sequence PRSoutputted from the random number generator 807 and supplies to thesub-information detector 809 a resultant sequence as a PE modulationrandom number sequence PERS.

The sub-information detector 809 detects a correlation between the PEmodulation random number sequence PERS from the PE modulator and each ofthe leading phase error signal LEAD ERR and the lagging phase errorsignal LAG ERR that are outputted from the clock extractor 804.

FIG. 10 is a circuit block diagram showing an example of an internalconfiguration of the sub-information detector 809. In FIG. 10, thesub-information detector is composed of a selector 1001, an integrator1002, a threshold value judging unit 1003, and a sub-information updatetiming generator 1004.

The selector 1001 is formed of two switching circuits each having twoinputs and one output. When the PE modulation random number sequencePERS from the PE modulator 808 is at the logic “H” level, the selector1001 allows the leading phase error signal LEAD ERR and the laggingphase error signal LAG ERR to pass through a positive input terminal (+)and a negative input terminal (−) of the integrator 1002, respectively.Further, when the PE modulation random number sequence PERS is at thelogic “L” level, the selector 1001 allows them to be crossed and passthrough the negative input terminal (−) and the positive input terminal(+) of the integrator 1002, respectively.

The integrator 1002 is a differential input/bipolar output analogintegrator. When the sub-information detection enabling signal SIDE fromthe reproduced signal processing circuit 805 is at the logic “H” level,the integrator 1002 adds areas of pulses inputted to the positive inputterminal to accumulate a resultant value, concurrently therewithsubtracts areas of pulses inputted to the negative input terminal toaccumulate a resultant value, and outputs to the threshold value judgingunit 1003 an analog signal corresponding to the accumulated areas.Further, when the sub-information detection enabling signal SIDE is atthe logic “L” level, the integrator 1002 retains a value resulting fromthe most recent accumulation. When a sub-information update signal(SIUD) is outputted from the sub-information update timing generator1004, the integrator 1002 clears the retained value resets the value tozero).

As a result, during a period of time when the PE modulation randomnumber sequence PERS outputted from the PE modulator 808 is at the logic“H” level, the integrator 1002 adds areas of pulses that occur in theleading phase error signal LEAD ERR to accumulate a resultant value andsubtracts areas of pulses that occur in the lagging phase error signalLAG ERR to accumulate a resultant value. Further, during a period oftime when the PE modulation random number sequence PERS is at logic “L”,the integrator 1002 subtracts areas of pulses that occur in the leadingphase error signal LEAD ERR to accumulate a resultant value and addsareas of pulses that occur in the lagging phase error signal LAG ERR toaccumulate a resultant value. Then, the integrator 1002 outputs ananalog voltage corresponding to the accumulated value.

Therefore, in the case where a positive correlation continues in whichpulses occur only in the leading phase error signal LEAD ERR during aperiod of time when the PE modulation random number sequence PERS is atthe logic “H” level and pulses occur only in the lagging phase errorsignal LAG ERR during a period of time when the PE modulation randomnumber sequence PERS is at the logic “L”, the output voltage of theintegrator 1002 increases in a positive direction. Conversely, in thecase where a negative correlation continues in which pulses occur onlyin the lagging phase error signal LAG ERR during a period of time whenthe PE modulation random number sequence PERS is at the logic “H” leveland pulses occur only in the leading phase error signal LEAD ERR duringa period of time when the PE modulation random number sequence PERS isat the logic “L” level, the output voltage of the integrator 1002decreases in a negative direction. Further, in the case where none ofthese correlations exists due to a difference in, for example, initialvalue from the random number initial value generator 806, that is, inthe case where pulses occur randomly in the leading phase error signalLEAD ERR and the lagging phase error signal LAG ERR irrespective of thePE modulation random number sequence PERS, the frequencies of theoccurrence of pulses that occur respectively in those error signals aresubstantially the same, so that the output voltage of the integrator1002 approximates to a zero level.

The threshold value judging unit 1003 is formed of, for example, acomparator that judges to which section the output voltage of theintegrator 1002 belongs, among three voltage sections separated based ona positive threshold voltage and a negative threshold voltage that havebeen set in advance. At a point in time when the sub-information updatesignal SIUD from the sub-information update timing generator 1004 isinputted, the threshold value judging unit 1003 produces an output assub-information 1 bit at a time in the form of a code string and sets adetection flag (DF) to the logic “H” level. In this case, when theoutput voltage of the integrator 1002 is larger than a positivethreshold value, the code string is at the logic “L” level, and when theoutput voltage is smaller than a negative threshold value, the codestring is at the logic “H” level. Further, in the case where the outputvoltage of the integrator 1002 belongs to a section between both thethreshold values, the threshold value judging unit 1003 outputs thelogic “L” level as the detection flag DF.

The sub-information update timing generator 1004 generates a timing forupdating sub-information based on the inputted synchronization signalSYNC. The sub-information update signal SIUD is a pulse signal that isoutputted for every 3 frames with respect to frames other than leadingand final frames of each sector. The sub-information update signal SIUDdears the value of the integrator 1002 and updates a result of judgmentby the threshold value judging unit 1003.

The description is directed next to a reproducing action of the opticaldisk reproducing apparatus according to this embodiment by referring toFIG. 11. FIG. 11 is a detailed timing chart for signals in respectiveportions when sub-information is reproduced from a recorded mark on theoptical disk 801.

When the digital read-out signal DRD, which is generated using reflectedlight resulting from laser irradiation onto the modulated recorded markMRM on the optical disk 801, is inputted to the clock extractor 804, thechannel clock CHCLK is generated that is obtained by synchronizing bothedges of the digital read-out signal DRD with a phase of a rising edge.By the reproduced signal processing circuit 805, the digital read-outsignal DRD is sampled using the channel clock CHCLK, and it is checkedby comparison if it agrees with a specific synchronization pattern so asto seek a synchronization portion 1101 in data. When a pattern agreeingwith the synchronization pattern is detected, the synchronization signalSYNC is outputted, and the sub-information detection enabling signalSIDE of the logic “H” level is outputted with respect to a data portion1102 of each frame in which sub-information is superimposed (frame otherthan leading and final frames of each sector).

When the synchronization signal SYNC is outputted, the clock extractor804 dears an internal four-frequency divider and outputs the PE signaland the byte clock BCLK obtained by 16-frequency-division of the channelclock CHCLK. Further, the clock extractor 804 presets the disk inherentidentification information (of 64 bits, for example), which has beenstored in advance in the read-out information storing part 701 (FIG. 7),so as to initialize the random number generator 807, and the randomnumber generator 807 outputs the pseudo random number sequence PRS 1 bitat a time at a timing of the byte clock BCLK (for every 16 channelclocks). Using the pseudo random number sequence PRS and the PE signal,the PE modulator 808 generates the PE modulation random number sequencePERS such that a 8-channel clock section of the logic “H” level and a8-channel clock section of the logic “L” level are provided within every16 channel clocks.

The clock extractor 804 detects a phase error between a rising edge ofthe channel clock CHCLK and each edge of the digital read-out signalDRD. In the case where the edge of the digital read-out signal DRD isadvanced with respect to the rising edge of the channel clock CHCLK, theclock extractor 804 outputs the leading phase error signal LEAD ERR.Further, in the case where the edge of the digital read-out signal DRDis delayed with respect to the rising edge of the channel clock CHCLK,the clock extractor 804 outputs the lagging phase error signal LAG ERR.

In a period of time when the sub-information detection enabling signalSIDE is at the logic “H” level, during a period of time when the PEmodulation random number sequence PERS is at the logic “H” level, thesub-information detector 809 adds the leading phase error signal LEADERR and subtracts the lagging phase error signal LAG ERR. Further,during a period of time the PE modulation random number sequence PERS isat the logic “L” level, the sub-information detector 809 adds thelagging phase error signal LAG ERR and subtracts the leading phase errorsignal LEAD ERR. In FIG. 11, in a period of time starting from thebeginning of the data portion 1102, in which the pseudo random numbersequence PRS is at the logic “L” level, during a period of time when thePE modulation random number sequence PERS is at the “H” level, theleading phase error signal LEAD ERR is outputted, and during a period oftime when the PE modulation random number sequence PERS is at the logic“L” level, the lagging phase error signal LAG ERR is outputted, so thatthe output voltage (INTG) of the integrator 1002 (FIG. 10) included inthe sub-information detector 809 increases.

Thus, at a point in time when integration with respect to a section inwhich 1 bit of sub-information is recorded is completed (at a point intime when the sub-information update signal SIUD is outputted): in thecase where the output voltage of the integrator 1002 is higher than apositive threshold voltage, the logic “L” level is detected assub-information (at the same time, the logic “H” level is outputted asthe detection flag DF); in the case where the output voltage is lowerthan a negative threshold voltage, the logic “H” level is detected assub-information (at the same time, the logic “H” is outputted as adetection flag); and in the case where the output voltage lies betweenthe negative threshold voltage and the positive threshold voltage, thelogic “L” level is outputted as a detection flag.

FIG. 12 is a waveform chart showing a relationship between asub-information bit and the integral value INTG obtained by theintegrator 1002 included in the sub-information detector 809. In FIG.12, in a first sub-information superimposition section 1201, there is acorrelation with the pseudo random number sequence PRS initialized usingthe disk inherent identification information and the integral value INTGkeeps increasing to exceed a positive threshold value (PVT), so that thelogic “L” level is extracted as sub-information. Conversely, in a secondsub-information superimposition section 1202, there is an inversecorrelation with the pseudo random number sequence PRS initialized usingthe disk inherent identification information and the integral value INTGkeeps decreasing to exceed a negative threshold value (NVT), so that thelogic “H” level is extracted as sub-information.

Meanwhile, a third sub-information superimposition section shows a valueas the integral value INTG that is obtained in the case wheresub-information is duplicated from one optical disk A to another opticaldisk B. The sub-information recorded on the optical disk A is recordedin accordance with the pseudo random number sequence PRS initializedusing disk inherent identification information of the optical disk A,and thus the sub-information duplicated illegally to the another opticaldisk B also is correlated with the pseudo random number sequence PRSinitialized using the disk inherent identification information of theoptical disk A. Therefore, in the case of reproducing the optical diskB, since there is no correlation between a pseudo random number sequenceinitialized using disk inherent identification information of theoptical disk B and the duplicated sub-information, the integral valueINTG does not increase nor decrease and thus does not exceed thepositive threshold value PVT and the negative threshold value NVT,sub-information cannot be reproduced appropriately.

As described above, in this embodiment, in accordance with a pseudorandom number sequence that is initialized using an initial valuecalculated from medium inherent information recorded on an optical disk,an edge in the tangential direction of a recording mark is displaced toa position advanced or delayed by a slight amount, and thussub-information is recorded.

Thus, in the optical disk recording apparatus and the optical diskreproducing apparatus according to this embodiment, since whenperforming recording or reproduction of sub-information with respect tothe same optical disk, medium inherent information recorded on theoptical disk also is the same, it is possible to obtain a pseudo randomnumber sequence for recording or reproducing the sub-information that isinherent in the medium. Conversely, in the case where main informationand sub-information of an optical disk A are duplicated entirely toanother optical disk B, since the sub-information that has been recordedusing a pseudo random number sequence generated using medium inherentinformation of the optical disk A as an initial value is incompatiblewith a pseudo random number sequence generated using medium inherentinformation of the optical disk B as an initial value, thesub-information duplicated illegally to the optical disk B cannot bereproduced.

Conventionally, in the case of recording as sub-information copyrightmanagement information that requires secure information rewritingbetween media such as, for example, the possible number of times ofduplication and the number of times of transfer between media ofchargeable digital works recorded on an optical disk, if sub-informationis duplicated entirely to another medium, there has been a risk ofallowing the infinite number of times of duplication even with arestriction set on the possible number of times of copying. However,when the sub-information in this embodiment is used in recordingcopyright management information, even if the sub-information isduplicated entirely to another medium, because of a difference in diskinherent identification information that is a medium identifier, it ispossible to prevent reproduction of the illegally duplicatedsub-information, thereby allowing copyright management information ofdigital works and the like to be recorded securely.

Embodiment 2

An optical disk according to Embodiment 2 of the present invention hasinside itself apparatus nullification information for nullifyingrecording and reproduction by an apparatus. For example, in a DVD-RAM,as shown in FIG. 22, an encryption medium key bundle has been recordedin advance as apparatus nullification information in an inner rimcontrol area 2202. The encryption medium key bundle is generated byencrypting a medium key using a device key contained individually ineach proper apparatus. Such a case requires large capacity for recordingan encryption medium key bundle according to the number of apparatuses,and thus in order to reduce the capacity of the corresponding encryptionmedium key bundle, matrix type and tree type data structures have beenproposed. In an apparatus without a proper device key, it is impossibleto generate an appropriate medium key from an encryption medium keybundle recorded on an optical disk, so that encrypted digital worksrecorded on the optical disk cannot be decoded reproduced). Further, if,for example, an apparatus exists that has performed illegal duplicationof digital works by tampering with the apparatus, an encryption mediumkey that can be decoded using a device key of the apparatus tamperedwith is eliminated from the encryption medium key bundle on the opticaldisk. Thus, it is possible to nullify recording and reproduction ofdigital works with respect to an optical disk on which an updatedencryption medium key bundle is recorded

Meanwhile, a proper licensed apparatus has a proper device key insidethe apparatus and uses this device key to decode an encryption mediumkey bundle so that a proper medium key can be generated. Therefore,proper apparatuses can generate a proper medium key, thereby allowingcompatibility to be imparted among the apparatuses in terms of recordingor reproduction of digital works.

In an optical disk recording apparatus according to this embodiment, apseudo random number sequence is generated using an initial value thatis calculated from information (medium key) outputted as a result of anapparatus nullification process in which a proper medium key isgenerated from an encryption medium key bundle using a device key. Usinga value of the pseudo random number sequence, the optical disk recordingapparatus records sub-information, thereby allowing nullification of anapparatus to be achieved even in terms of recording of sub-information.

FIG. 13 is a conceptual diagram showing a signal connection relationshipbetween the optical disk and the optical disk recording apparatusaccording to Embodiment 2 of the present invention. In FIG. 13, theoptical disk recording apparatus according to this embodiment iscomposed of an apparatus nullification processing part 1301 in which amedium key for encrypting digital works to be recorded is decoded fromapparatus inherent information (device key) that is contained secretlyinside the apparatus and an encryption medium key bundle that can existand is obtained by encrypting the medium key using the apparatusinherent information; an information storing part 1302 that temporarilystores the medium key (of 64 bits, for example) outputted from theapparatus nullification processing part 1301; and an informationrecording part 1303 that simultaneously records main information andsub-information on an optical disk in accordance with a pseudo randomnumber sequence that is generated using an initial value calculated fromthe medium key stored temporarily in the information storing part 1302.

The information recording part 1303 has the same block configuration asthat of the information recording part 202 in the optical disk recordingapparatus according to Embodiment 1, which is shown in FIG. 3. By theinformation recording part 1303, in accordance with a pseudo randomnumber sequence that is generated using a medium key stored temporarilyin the information storing part 1302 as an initial value for a randomnumber generator, an edge in a tangential direction of a recording markis displaced to a position advanced or delayed by a slight amount, andthus sub-information is recorded.

FIG. 14 is a conceptual diagram showing a signal connection relationshipbetween the optical disk and an optical disk reproducing apparatusaccording to Embodiment 2 of the present invention. In FIG. 14, theoptical disk reproducing apparatus is an apparatus that reproduces maininformation and sub-information from an optical disk on which theabove-described encryption medium key bundle for nullifying an apparatusis recorded. The optical disk reproducing apparatus is composed of anapparatus nullification processing part 1401 that decodes a medium keyfrom an encryption medium key bundle that has been read out in advancefrom the optical disk and apparatus inherent information (device key)that is contained secretly inside the apparatus; an information storingpart 1402 that temporarily stores the medium key outputted from theapparatus nullification processing part 1401; and an informationreproducing part 1403 that simultaneously reproduces main informationand sub-information in accordance with a pseudo random number sequencethat is generated using an initial value calculated from the medium keystored temporarily in the information storing part 1402.

The apparatus nullification processing part 1401 has the same functionas that of the apparatus nullification processing part 1301 in theoptical disk recording apparatus, which is shown in FIG. 13. That is,the apparatus nullification processing part 1401 decodes a medium keyfrom an encryption medium key bundle that has been recorded in advancein an optical disk and the device key that is contained secretly insidethe reproducing apparatus. Thus, it is impossible to decode anappropriate medium key using an illegal device key, a nullified devicekey, or an adulterated encryption medium key bundle.

The information reproducing part 1403 generates a pseudo random numbersequence using as an initial value a medium key that has been decoded inadvance by the apparatus nullification processing part 1401 andreproduces sub-information based on a correlation of the generatedpseudo random number sequence with a phase error signal of an edge inthe tangential direction of a recorded mark to be reproduced, having thesame configuration as that of the information reproducing part 702 inthe optical disk reproducing apparatus.

Also in this embodiment, as described in Embodiment 1 by referring toFIG. 12, in the first sub-information superimposition section 1201, thelogic “L” level is extracted as a sub-information bit, and in the secondsub-information superimposition section 1202, the logic “H” level isextracted as a sub-information bit.

The third sub-information superimposition section 1203 shows an integralvalue of an optical disk on which sub-information is recorded by anullified apparatus as described in this embodiment or an integral valueresulting from reproducing the sub-information by the nullifiedapparatus. In a nullified apparatus, it is impossible to generate anaccurate medium key from apparatus nullification information (encryptionmedium key bundle) that is recorded on an optical disk and apparatusinherent information (device key) that is contained secretly inside theapparatus. Therefore, in the case of reproducing, using an accuratemedium key, sub-information recorded in accordance with a pseudo randomnumber sequence initialized using such an illegal medium key, or in thecase of reproducing sub-information, which is recorded in accordancewith a pseudo random number sequence initialized using an accuratemedium key, in accordance with a pseudo random number sequenceinitialized using an illegal medium key of a nullified apparatus, thereis no correlation between the pseudo random number sequence on arecording side and the pseudo random number sequence on a reproductionside. Therefore, the integral value INTG does not increase nor decrease,and thus the sub-information is not extracted appropriately.

As described above, in this embodiment, the apparatus nullificationprocessing parts 1301 and 1401 are provided that can performnullification of an apparatus using apparatus inherent information thatis contained secretly inside an apparatus and an encryption medium keybundle that has been recorded in advance on an optical disk. An initialvalue is calculated from information (medium key) outputted from theapparatus nullification processing parts 1301 and 1401, and inaccordance with a pseudo random number sequence initialized using thecalculated initial value, sub-information is recorded or reproduced.

As in a conventional technique, in a method of recording sub-informationbased on a correlation with a specific pseudo random number sequence,even an apparatus in which main information recording and reproductionare nullified can record sub-information appropriately. Further, in amethod of reproducing sub-information based on a correlation with aspecific pseudo random number sequence, even an apparatus in which maininformation recording and reproduction are nullified can reproducesub-information appropriately. Therefore, in the case where copyrightmanagement information such as information for managing the number oftimes of duplication of digital works is recorded as sub-information,even with the advent of an apparatus, obtained by tamperings forexample, that can perform an infinite number of duplications of digitalworks by illegally rewriting the information for managing the number oftimes of duplication recorded as the sub-information, there is no way ofnullifying recording and reproduction of the sub-information by theapparatus.

However, this embodiment has a mechanism in which sub-information can berecorded or reproduced appropriately only by using a pseudo randomnumber sequence that is initialized using information (medium key)obtained as a result of an apparatus nullification process. Therefore,even with the advent of an apparatus that illegally rewritessub-information by tampering or the like, by updating from then on anencryption medium key bundle of each medium being distributed, it ispossible to nullify recording and reproduction of sub-information withrespect to a medium having the updated encryption medium key bundle.

As discussed in the foregoing description, according to this embodiment,in the case of recording copyright management information assub-information, even in a situation where by, for example, tamperingwith an apparatus, digital works are duplicated illegally, bydistributing optical disks having updated encryption medium key bundles,it is possible to suppress damage to a minimum degree.

Embodiment 3

An optical disk recording apparatus according to Embodiment 3 of thepresent invention has inherent information for identifying an apparatus.For example, apparatus inherent information in a DVD-RAM recordingapparatus is referred to as a device key. By decoding an encryptionmedium key bundle that has been recorded in advance on an optical diskusing this device key, a medium key for encrypting digital works isgenerated. As has already been described in Embodiment 2, by theapparatus inherent information and the encryption medium key bundle onthe optical disk, recording and reproduction of main information arenullified.

In the optical recording apparatus according to this embodiment,sub-information is recorded based on apparatus inherent information soas to disable reproduction of the sub-information by apparatuses otherthan the apparatus that has performed recording of the sub-information.

FIG. 15 is a conceptual diagram showing a signal connection relationshipbetween an optical disk and the optical disk recording apparatusaccording to Embodiment 3 of the present invention. In FIG. 15, theoptical disk recording apparatus secretly contains apparatus inherentinformation inside the apparatus and includes an information recordingpart 1501 that simultaneously records main information andsub-information on an optical disk in accordance with a pseudo randomnumber sequence that is obtained using the apparatus inherentinformation as an initial value.

The information recording part 1501 has the same block configuration asthat (FIG. 3) of each of the information recording part 202 inEmbodiment 1 shown in FIG. 2 and the information recording part 1303 inEmbodiment 2 shown in FIG. 13. By the information recording part 1501,in accordance with a pseudo random number sequence that is generatedusing apparatus inherent information contained inside the apparatus asan initial value for a pseudo random number generator, an edge in atangential direction of a recording mark is displaced to a positionadvanced or delayed by a slight amount, and thus sub-information isrecorded. Also in this embodiment, similarly to Embodiments 1 and 2, aninitial value generating part 303 of the optical disk recordingapparatus has a configuration in which apparent inherent informationcontained inside the apparatus is outputted in an as-is state.

FIG. 16 is a conceptual diagram showing a signal connection relationshipbetween an optical disk and an optical disk reproducing apparatusaccording to Embodiment 3 of the present invention. In FIG. 16,similarly to the optical disk recording apparatus according to thisembodiment, the optical disk reproducing apparatus according to thisembodiment contains apparatus inherent information that is inherent ineach apparatus and includes an information reproducing part 1601 thatsimultaneously reproduces main information and sub-information inaccordance with a pseudo random number sequence that is generated usingthe apparatus inherent information as an initial value.

The information reproducing part 1601 generates a pseudo random numbersequence by using as an initial value apparatus inherent informationthat is contained individually in each apparatus and reproducessub-information based on a correlation between the generated pseudorandom number sequence and a phase error signal of an edge in thetangential direction of a recorded mark to be reproduced, having thesame configuration as that of the information reproducing part 702 inEmbodiment 1 shown in FIG. 8.

Also in this embodiment, as described in Embodiment 1 by referring toFIG. 12, in the first sub-information superimposition section 1201, thelogic “L” level is extracted as a sub-information bit, and in the secondsub-information superimposition section 1202, the logic “H” level isextracted as a sub-information bit.

Meanwhile, the third sub-information superimposition section 1203 showsan integral value obtained in the case of performing reproduction withrespect to an optical disk, on which main information andsub-information are recorded by the optical disk recording apparatusaccording to this embodiment, by an apparatus different from theapparatus that has performed recording with respect to the optical disk.In this case, since the sub-information is recorded in accordance with apseudo random number sequence that is initialized using informationinherent in the recording apparatus, there is no correlation between thesub-information and a pseudo random number sequence that is initializedusing information inherent in a reproducing apparatus different from therecording apparatus. Therefore, the integral value does not increase nordecrease, and thus the sub-information is not extracted appropriately.

As described above, in this embodiment, a pseudo random number sequenceis generated based on apparatus inherent information that is containedsecretly inside an apparatus, and recording or reproduction ofsub-information is performed in accordance with this pseudo randomnumber sequence, thereby allowing sub-information to be recorded thatcannot be reproduced by apparatuses other than an apparatus that hasperformed recording.

In a conventional optical disk, in the case where contents delivered ona network are recorded on the optical disk, there is a possibility thatmedia themselves, on which digital works are recorded, are distributedat low cost on a secondhand market, which is detrimental to the benefitof digital work distributors. However, according to this embodiment, byrecording an encryption key of main information as sub-information, theabove-mentioned problem can be solved.

Embodiments 1 and 2 described sub-information that was obtained by,according to the present invention, allowing a recording mark to bedeformed slightly in accordance with a pseudo random number sequencerelated to medium inherent information or apparatus nullificationinformation and thus nullified sub-information inherent to a medium orrecording and reproduction of a specific apparatus. However, needless tosay, the present invention is not limited to these embodiments.

For example, Embodiments 1 and 2 described the structure in which anedge in a tangential direction of a recording mark was displaced to aposition advanced or delayed in accordance with a generated pseudorandom number sequence so as to allow the recording mark to be deformedslightly, and thus sub-information was recorded. However, the presentinvention can be applied to techniques in which sub-information isrecorded so that the sub-information is superimposed on main informationin accordance with a pseudo random number sequence and thesub-information is recorded or reproduced based on a correlation with anequivalent pseudo random number sequence. In an example of suchtechniques, recording power is controlled in accordance with a pseudorandom number sequence so as to allow a recording mark to be deformedslightly. In another example of the techniques, a laser beam isdisplaced in a radial direction in accordance with a pseudo randomnumber sequence so as to perform radial modulation of a recording mark.In still another example of the techniques, a bit error of maininformation is caused in accordance with a pseudo random number sequenceso as to record sub-information. In yet another example of thetechniques, special modulation of main-information is performed inaccordance with a pseudo random number sequence so as to recordsub-information. Among the above-mentioned examples, the radialmodulation of a recording mark performed by displacement of a laser beanin a radial direction in accordance with a pseudo random number sequencewill be described below in Embodiment 4.

Embodiment 4

FIG. 17 is a diagrammatic view showing an example of recorded markscontaining sub-information that are formed on an optical disk accordingto Embodiment 4 of the present invention. In FIG. 17, recorded marks arenot displaced in a radial direction in a synchronization portion 1701,while in a track (N) of a data portion 1702, a recorded mark 1703 isdisplaced by Δr in an outer rim direction, and a recorded mark 1704 isdisplaced by Δr in an inner rim direction. The same also applies to atrack (N+2).

Furthermore, in a track (N+1), a recorded mark 1705 is a frame to whichdisk inherent information is imparted and thus is not displaced in aradial direction. This also applies to a track (N+3), a track (N+4), anda track (N+5).

As shown in FIG. 17, a track pitch 1706 between a track (for example,the track (N)) in which a recorded mark is displaced in the radialdirection of the optical disk and a track (for example, the track (N+1))in which a recorded mark is not displaced is larger than a track pitch1707 between tracks (for example, between the track (N+3) and the track(N+4)) in each of which a recorded mark is not displaced.

FIG. 18 is a block diagram showing an example of a configuration of anoptical disk recording apparatus according to Embodiment 4 of thepresent invention. The optical disk recording apparatus according tothis embodiment is different from Embodiment 1 shown in FIG. 3 in thatthe phase modulator 307 is removed whereas a radial modulator 1801 andan electrode 1802 are added. Other configurations and functions are thesame as those shown in FIG. 3 and thus are denoted by like referencenumerals with duplicate descriptions thereon omitted.

During a period of time when a displacement enabling signal (SE)outputted from a timing generator 301 is at the logic “H” level, inaccordance with a logic level of a PE modulation random number sequencePERS outputted from a PE modulator 306, the radial modulator 1801applies an analog displacement control voltage (ASC) that is a positivepotential or a negative potential to the electrode 1802. According tothis analog displacement control voltage ASC, the electrode 1802displaces a recording beam outputted from a recording head 309 to anouter rim direction or an inner rim direction of an optical disk 310.

FIG. 19 is a timing chart for signals in respective portions when arecording mark containing sub-information is formed on an optical diskby the optical disk recording apparatus according to this embodiment. InFIG. 19, like names indicate like signals that are shown in FIG. 6referred to in the description of Embodiment 1.

In FIG. 19, when switching from a synchronization portion 1901 to a dataportion 1902 is detected by the timing generator 301, the displacementenabling signal SE attains the logic “H” level. In the case where the PEmodulation random number sequence PERS outputted from the PE modulator306 is “1”, the radial modulator 1801 outputs a positive voltage (+V) asthe analog displacement control voltage ASC. In this case, for example,a recording mark 1903 is formed so as to be displaced by Δd in the outerrim direction of the optical disk 310. In the case where the PEmodulation random number sequence PERS is “0”, the radial modulator 1801outputs a negative voltage (−V) as the analog displacement controlvoltage ASC. In this case, for example, a recording mark 1904 is formedso as to be displaced by Δd in the inner rim direction of the opticaldisk 310.

FIG. 20 is a block diagram showing an example of a configuration of anoptical disk reproducing apparatus according to Embodiment 4 of thepresent invention. In Embodiment 1, as shown in FIG. 8, the leadingphase error signal LEAD ERR and the lagging phase error signal LAG ERRwere generated by the clock extractor 804, and by the sub-informationdetector 809, a correlation was established between the PE modulationrandom number sequence PERS and each of the leading phase error signalLEAD ERR and the lagging phase error signal LAG ERR so as to detectsub-information by slight displacement of an edge in a tangentialdirection of a recorded mark. In contrast to this, in a configurationaccording to this embodiment, an analog TE (Tracking Error) signal (ATE)read out from a reproducing head 802 is converted into a digital TEsignal (DTE) by an AD converter 2001. By a sub-information detector2002, an outer rim side displacement signal and an inner rim sidedisplacement signal of a recorded mark are extracted from the digital TEsignal DTE. A correlation is established between the PE modulationrandom number sequence PERS and each of these outer rim sidedisplacement signal and the inner rim side displacement signal so as todetect sub-information by displacement of the recorded mark itself in aradial direction.

FIG. 21 is a timing chart for signals in respective portions whensub-information is reproduced from a recorded mark on an optical disk bythe optical disk reproducing apparatus according to this embodiment. InFIG. 21, like names indicate like signals that are shown in FIG. 11referred to in the description of Embodiment 1.

In FIG. 21, when switching from a synchronization portion 2101 to a dataportion 2102 is detected by a reproduced signal processing circuit 805,a sub-information detection enabling signal SIDE attains the logic “H”level. In the case where a PE modulation random number sequence PERSoutputted from a PE modulator 808 is “1” and a digital TE signal DTEindicates an outer rim direction displacement signal, or the PEmodulation random number sequence PERS is “0” and the digital TE signalDTE indicates an inner rim direction displacement signal, an outputvoltage INTG of an integrator included in the sub-information detector2002 increases to exceed a positive threshold value. Thus, the logic “L”level is detected as sub-information.

Though not shown in FIG. 21, in the case where the PE modulation randomnumber sequence PERS is “1” and the digital TE signal DTE indicates aninner rim direction displacement signal, or in the case where the PEmodulation random number sequence PERS is “0” and the digital TE signalDTE indicates an outer rim direction displacement signal, the outputvoltage INTG of the integrator included in the sub-information detector2002 decreases to exceed a negative threshold value. Thus, the logic “H”level is detected as sub-information.

In each of the above-described embodiments, main information is notlimited to an optically readable recording mark, and a structure inwhich the main information is read out using a magnetic force, heat orthe like also is possible.

Furthermore, by combining Embodiment 1 with Embodiment 2, it is possibleto record sub-information that is inherent in a medium, disables illegalduplication between media, and nullifies recording and reproduction ofthe sub-information by a specific apparatus. This can be achieved by amethod in which a pseudo random number sequence inherent in a medium anda pseudo random number sequence that allows nullification are recordedwhile being switched with respect to every unit area in whichsub-information is to be recorded (for example, a sector unit, a frameunit, an ECC (Error Correction Code) block unit, a track unit).Alternatively, this can be achieved also by, for example, as in aDVD-RAM, using a pseudo random number sequence related to a medium keygenerated as a result of an apparatus nullification process and a mediuminherent key generated from disk inherent identification informationthat is medium inherent information.

Furthermore, Embodiment 1 described the structure in which mediuminherent information was used in an as-is state as an in initial valueof a pseudo random number sequence. However, a structure also ispossible in which a result of encryption of medium inherent informationor a bit operation such as bit extension, bit shortening, bit scramblingor the like is used as an initial value. Similarly, Embodiment 2 used acontents encryption key (medium key) in an as-is state as an initialvalue of a pseudo random number sequence. However, a structure also ispossible in which a result of encryption of a contents encryption key ora bit operation such as bit extension, bit shortening, bit scrambling orthe like is used as an initial value.

As discussed in the foregoing description, according to the presentinvention, even if main information and sub-information are duplicatedfrom an information recording medium, on which an encryption key ofdigital contents to be recorded is recorded as sub-information, entirelyto another information recording medium, the sub-information cannot bereproduced from the another information recording medium, so that it ispossible to suppress reproduction of the duplicated digital contents.

Furthermore, in the case where an initial value is publicized in a givenapparatus, recording and reproduction of sub-information by theapparatus can be nullified.

1. An information recording medium in which a recording mark is formedas main information by switching a signal level at a predeterminedinterval of a reference signal, wherein sub-information is recorded soas to be superimposed on the main information by deformation of a shapeor a pattern of the recording mark or positional displacement of therecording mark in accordance with the sub-information, thesub-information being subjected to data conversion based on mediuminherent information or apparatus nullification information that isrecorded on the information recording medium.
 2. The informationrecording medium according to claim 1, wherein the medium inherentinformation is recorded irreversibly so that only reproduction can beperformed with respect to the medium inherent information.
 3. Theinformation recording medium according to claim 2, wherein the mediuminherent information is recorded in a burst cutting area (BCA).
 4. Theinformation recording medium according to claim 1, wherein the dataconversion of the sub-information is a correlation operation of thesub-information with respect to a pseudo random number sequence that isgenerated using the medium inherent information or the apparatusnullification information as an initial value.
 5. The informationrecording medium according to claim 1, wherein the data conversion ofthe sub-information is a correlation operation of the sub-informationwith respect to a pseudo random number sequence that is generated usingas an initial value a contents encryption key obtained using the mediuminherent information or the apparatus nullification information.
 6. Theinformation recording medium according to claim 5, wherein the apparatusnullification information is an encryption key set for encrypting themain information of the information recording medium.
 7. An informationrecording apparatus, comprising: a main information recording unit thatrecords, in synchronization with a predetermined reference signal, maininformation by forming a recording mark at discrete reference positionson an information recording medium; a random number sequence generatingunit that generates a pseudo random number sequence using as an initialvalue medium inherent information or apparatus nullification informationthat is recorded on the information recording medium; and asub-information recording unit that records sub-information so that thesub-information is superimposed on the main information by deformationof a shape or a pattern of the recording mark or positional displacementof the recording mark, based on the sub-information and the pseudorandom number sequence generated by the random number sequencegenerating unit.
 8. The information recording apparatus according toclaim 7, wherein the medium inherent information has been read out inadvance from a burst cutting area (BCA) in which the medium inherentinformation is recorded irreversibly so that only reproduction can beperformed with respect to the medium inherent information.
 9. Theinformation recording apparatus according to claim 7, wherein theapparatus nullification information is an encryption key set forencrypting the main information, and the initial value for the randomnumber sequence generating unit is at least one encryption key set. 10.An information reproducing apparatus, comprising: a main informationreproducing unit that reproduces main information from a recorded markhaving a length that is an integral multiple of a discrete referenceinterval on an information recording medium; a clock extracting unitthat extracts a clock that is synchronized with the reference intervalfrom a reproduced signal obtained when the recorded mark is reproduced;a random number sequence generating unit that reads out medium inherentinformation or apparatus nullification information that is recorded onthe information recording medium and generates a pseudo random numbersequence using the medium inherent information or the apparatusnullification information as an initial value; and a sub-informationreproducing unit that reproduces sub-information based on the reproducedsignal reproduced by the main information reproducing unit, the clockextracted by the clock extracting unit, and the pseudo random numbersequence generated by the random number sequence generating unit. 11.The information reproducing apparatus according to claim 10, wherein bythe sub-information reproducing unit, the medium inherent informationhas been read out in advance from a burst cutting area (BCA) in whichthe medium inherent information is recorded irreversibly so that onlyreproduction can be performed with respect to the medium inherentinformation
 12. The information reproducing apparatus according to claim10, wherein the apparatus nullification information is an encryption keyset for encrypting the main information, and the initial value for therandom number sequence generating unit is at least one encryption keyset.